:root {
  color-scheme: light;
  --bg-top: #f4efe6;
  --bg-bottom: #dfe9f7;
  --panel-bg: rgba(255, 255, 255, 0.82);
  --panel-border: rgba(47, 62, 85, 0.12);
  --text-main: #203047;
  --text-muted: #5e6d82;
  --accent: #1d6fd8;
  --accent-strong: #1553a4;
  --accent-soft: rgba(29, 111, 216, 0.12);
  --success: #157347;
  --error: #b64a36;
  --warning: #d27d00;
  --shadow: 0 24px 60px rgba(27, 47, 74, 0.16);
  --radius-xl: 28px;
  --radius-lg: 20px;
  --radius-md: 14px;
  --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "Cascadia Code", "Consolas", monospace;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  color: var(--text-main);
  background:
    radial-gradient(circle at top left, rgba(255, 255, 255, 0.9), transparent 32%),
    linear-gradient(180deg, var(--bg-top), var(--bg-bottom));
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    linear-gradient(120deg, rgba(255, 255, 255, 0.28), transparent 38%),
    radial-gradient(circle at bottom right, rgba(29, 111, 216, 0.12), transparent 24%);
  pointer-events: none;
}

.app-shell {
  position: relative;
  min-height: 100vh;
  padding: 40px 20px;
  display: grid;
  place-items: center;
}

.panel {
  width: min(100%, 760px);
  display: grid;
  gap: 24px;
  padding: 28px;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-xl);
  background: var(--panel-bg);
  box-shadow: var(--shadow);
  backdrop-filter: blur(18px);
}

.panel-header {
  display: grid;
  gap: 10px;
}

.eyebrow {
  margin: 0;
  font-size: 0.86rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-strong);
}

h1,
h2,
p {
  margin: 0;
}

h1 {
  font-size: clamp(2rem, 4vw, 2.8rem);
  line-height: 1.05;
}

h2 {
  font-size: 1.1rem;
}

.subtitle {
  max-width: 40rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.output-card,
.controls,
.length-card,
.option-card {
  border: 1px solid rgba(47, 62, 85, 0.1);
  border-radius: var(--radius-lg);
  background: rgba(255, 255, 255, 0.74);
}

.output-card,
.controls {
  padding: 22px;
}

.section-heading,
.length-header,
.output-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.output-card,
.controls {
  display: grid;
  gap: 18px;
}

.password-output,
.length-number,
.primary-button,
.secondary-button {
  border: 1px solid transparent;
  font: inherit;
}

.password-output,
.length-number {
  border-color: rgba(47, 62, 85, 0.16);
  border-radius: var(--radius-md);
  background: rgba(248, 251, 255, 0.95);
}

.password-output {
  flex: 1 1 auto;
  min-width: 0;
  padding: 16px 18px;
  font-family: var(--font-mono);
  font-size: 1rem;
  letter-spacing: 0.04em;
  color: var(--text-main);
}

.length-card {
  display: grid;
  gap: 14px;
  padding: 18px;
}

.length-number {
  width: 96px;
  padding: 10px 12px;
  text-align: center;
}

.length-scale {
  display: flex;
  justify-content: space-between;
  color: var(--text-muted);
  font-size: 0.9rem;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.option-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.option-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px;
  color: var(--text-main);
}

.option-card-wide {
  grid-column: 1 / -1;
}

.option-card input {
  width: 18px;
  height: 18px;
  accent-color: var(--accent);
  flex: 0 0 auto;
}

.primary-button,
.secondary-button {
  padding: 13px 18px;
  border-radius: 999px;
  cursor: pointer;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}

.primary-button {
  color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  box-shadow: 0 14px 30px rgba(29, 111, 216, 0.24);
}

.secondary-button {
  color: var(--accent-strong);
  background: var(--accent-soft);
}

.primary-button:hover,
.secondary-button:hover {
  transform: translateY(-1px);
}

.primary-button:disabled,
.secondary-button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
  transform: none;
  box-shadow: none;
}

.status-message {
  min-height: 1.6em;
  color: var(--text-muted);
}

.status-message[data-tone="success"] {
  color: var(--success);
}

.status-message[data-tone="error"] {
  color: var(--error);
}

.strength {
  display: inline-flex;
  align-items: center;
  padding: 8px 12px;
  border-radius: 999px;
  font-size: 0.92rem;
  background: rgba(47, 62, 85, 0.08);
}

.strength-weak {
  color: var(--error);
  background: rgba(182, 74, 54, 0.12);
}

.strength-medium {
  color: var(--warning);
  background: rgba(210, 125, 0, 0.12);
}

.strength-strong {
  color: var(--success);
  background: rgba(21, 115, 71, 0.12);
}

.strength-neutral {
  color: var(--text-muted);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 720px) {
  .app-shell {
    padding: 20px 14px;
  }

  .panel {
    padding: 20px;
  }

  .section-heading,
  .length-header,
  .output-row {
    align-items: stretch;
    flex-direction: column;
  }

  .option-grid {
    grid-template-columns: 1fr;
  }

  .option-card-wide {
    grid-column: auto;
  }

  .length-number,
  .primary-button,
  .secondary-button {
    width: 100%;
  }
}